Roch microwave turned on but not heating

How to Repair a Faulty Microwave Oven: The Easy Way

If your microwave oven suddenly stops heating, makes a loud humming noise, or starts sparking near the side wall, the most likely culprit is a faulty microwave magnetron.

The good news?

Replacing the magnetron is far cheaper than buying a new microwave oven.

At KSh 1,499, a replacement microwave magnetron is one of the most cost-effective appliance repairs you can make today, especially when the cheapest new microwave ovens are retailing from KSh 7,500 and above.

What Is a Microwave Magnetron?

A microwave magnetron is the core component responsible for generating microwave energy that heats your food. It converts electrical energy into high-frequency microwave radiation, which is then directed into the cooking chamber via the waveguide.

If the magnetron fails, your microwave will still power on, light up, and spin, but it won’t heat food.

It works together with:

  • High-voltage capacitor
  • High-voltage diode
  • Waveguide
  • Antenna cap
  • Waveguide Mica Cover

If any of these components fail, heating efficiency drops or stops completely.

Common Microwave Magnetron Failure Symptoms

You may need a magnetron replacement if you notice:

  • Microwave runs but food stays cold
  • Loud buzzing or humming during operation
  • Burning smell without visible sparks
  • Microwave trips power or shuts down mid-cycle
  • Visible damage to the magnetron antenna

Important tidbit: Sparking alone doesn’t always mean the magnetron is bad, this is why it’s crucial to replace the waveguide cover first as a diagnostic step.

Read First: 👉 Microwave Waveguide Cover – Cheapest Sparking Fix (KES 300)

Magnetron Antenna Cap vs Magnetron Failure

Dismantled for a demo Microwave Oven Magnetron with a burned out antenna cap

Before replacing the entire magnetron, also inspect the antenna cap.

ComponentCostReplace First?
Waveguide CoverKES 300✅ Always
Magnetron Antenna CapLow✅ If sparking continues
MagnetronHigh❌ Last step

This elimination approach keeps repair costs low and avoids unnecessary part replacement.

How Long Does a Microwave Magnetron Last?

On average, a microwave magnetron is designed to last 2,000 to 4,000 operating hours, which translates to about 2–5 years for typical household use.

If installed correctly, a new replacement magnetron can keep your microwave running for another 2 years or more, depending on:

  • Usage frequency
  • Proper ventilation
  • Clean waveguide area
  • Stable power supply

This makes magnetron replacement a very practical alternative to buying a new microwave.

Why Replacing the Magnetron Makes Financial Sense

OptionCost (KSh)
Replace magnetron1,499
Replace waveguide cover300
Buy new microwave oven7,500+

For less than KSh 1,800, you can restore a microwave that would otherwise be discarded.

Instant Device Cash sale receipt for a Microwave Oven Magnetron and a Waveguide Mica Cover issued to a customer on December 22, 2026.

Why Most Customers Buy the Magnetron & Waveguide Cover Together

Most experienced technicians, and DIY users, replace both the magnetron and the microwave waveguide cover for best results.

Why this works:

  • A burnt or carbonized waveguide cover can cause sparking
  • Sparking can damage the new magnetron antenna
  • A fresh waveguide cover protects your investment

This two-part replacement strategy minimizes repeat failures and extends appliance life.

  1. MagnetronKSh 1499
  2. Microwave Oven Waveguide Cover – KSh 300

Is It Safe to Replace a Magnetron Yourself?

Not recommended for DIY users.

Magnetrons are connected to high-voltage capacitors that can store lethal charge even when unplugged.

✔️ Recommended approach:

  • DIY: Waveguide cover replacement
  • Technician: Magnetron diagnosis & replacement

Smart Repair Strategy (Cost-Saving Workflow)

  1. Replace waveguide cover (KES 300)
  2. Test microwave
  3. If sparking persists → inspect antenna cap
  4. Only then consider magnetron replacement

This approach minimizes risk and repair cost.

Buy Microwave Magnetron from Instant Device, Nairobi

Shop Location: B1 (Basement) Accra Trade Center, Nairobi.
Call / WhatsApp: 0768679055 | 0114746858

We stock replacement microwave magnetrons and custom-cut waveguide covers, ready for same-day dispatch.

Save money. Reduce waste. Keep your microwave running.

How We Handle Orders Outside Nairobi (e.g. Thika, Mombasa, Kakamega)

For customers outside Nairobi, we follow a simple and transparent process:

  1. Choose your delivery method
    – Bus company or package courier serving your route from Nairobi.
  2. Confirm your order
    – We deliver the item to the Nairobi office of your chosen company
  3. Verification step
    – Ask the courier office to confirm the item condition for you
  4. Payment
    – Pay us the item cost + KSh 100 dispatch fee
    – Item is packaged only after payment
  5. Courier fee
    – Bus companies typically charge ~KSh 300 for small package delivery
    – This is an upfront payment at their Nairobi office before dispatch

This method is cheap, fast, and trusted by our coastal customers.

👉 Order Your Microwave Magnetron Today

  • 0768679055 Call or WhatsApp Instant Device. Nationwide delivery available.
Waveguide cover installed inside a Microwave oven with burn marks indicating magnetron protection failure

How to Buy a Microwave Waveguide Cover in Nairobi

If your microwave oven has started sparking, flashing, or producing crackling sounds, don’t rush to replace expensive parts just yet.

In most cases, the issue is caused by a burnt microwave waveguide cover, a small, low-cost component that protects the waveguide opening.

At Instant Device, we sell precision-cut microwave waveguide covers (sketched directly from the original factory part) for only KES 299, making this one of the most cost-effective microwave repairs in Kenya.

👉 Buy Microwave Waveguide Cover (KES 299 Only!)

What Is a Microwave Waveguide Cover?

A microwave oven waveguide cover is a thin mica sheet installed inside the microwave cavity that protects the waveguide opening while allowing microwave energy to pass through safely.

Its main functions:

  • Prevent food particles and grease from entering the waveguide
  • Protect the magnetron antenna from contamination
  • Reduce internal arcing and sparking
  • Extend the lifespan of the microwave

Over time, heat, moisture, and grease cause the waveguide cover to burn, carbonize, or crack, leading to visible sparks.

Why a Damaged Waveguide Cover Causes Sparking

When the waveguide cover becomes:

  • Burnt
  • Grease-soaked
  • Cracked
  • Carbonized

…it starts conducting electricity unevenly, resulting in arcing (sparking) inside the microwave cavity.

⚠️ This is often mistaken for a magnetron failure, yet replacing the waveguide cover solves the problem in a large percentage of cases.

Why Replacing the Waveguide Cover Is the Smart First Repair

Replacing the waveguide cover is both a repair and a diagnostic step.

Why it’s cost-effective:

  • Costs only KES 299
  • Easy to replace (no special tools)
  • Helps eliminate more complex faults
  • Prevents unnecessary disposal of a working microwave

Smart diagnostic logic:

  1. Replace the waveguide cover
  2. If sparking stops → problem solved cheaply
  3. If sparking continues → inspect:
    • Magnetron antenna cap
    • Magnetron unit
    • Waveguide interior

👉 This elimination method keeps repair costs low and avoids guesswork.

Related: Microwave Magnetron Explained – Symptoms, Costs & Diagnosis

Microwave Waveguide Cover vs Magnetron: Which Should You Replace First?

ComponentCost RangeDifficultyReplace First?
Waveguide CoverKES 299Very EasyYES
Magnetron Antenna CapLowEasyIf sparking persists
MagnetronHighComplexLast resort

👉 Order Waveguide Cover Before Replacing Expensive Parts

Why Buy Your Waveguide Cover from Instant Device?

At Instant Device, our waveguide covers are:

  • Cut to size from original factory patterns
  • Made from microwave-safe material
  • Suitable for most microwave oven models
  • Ideal for home users, technicians & restaurants

Retail Price: KES 299

👉 Shop Microwave Waveguide Covers Online

Where to Buy Microwave Waveguide Covers in Nairobi

📍 Instant Device – Nairobi
We offer walk-in purchases and technical guidance for microwave repairs.

📞 Call / WhatsApp Orders:
+254 768679055/ +254114746858

Nationwide Delivery: Migori, Namanga, Mombasa & Beyond

For customers outside Nairobi, we offer flexible shipping via bus companies or package couriers.

How the Process Works:

1️⃣ Choose a bus or courier company serving Nairobi → Bamburi / Mombasa
2️⃣ Confirm your order with us
3️⃣ We deliver the item to the courier’s Nairobi office
4️⃣ Ask their staff to confirm the item
5️⃣ Pay us:

  • Item cost KES 299
  • KES 100 dispatch fee

Packaging is done only after payment.

Courier charge:
Bus companies typically charge KES 200, paid directly to them on pickup.

Frequently Asked Questions (FAQ)

Can I use metal or cardboard instead of a mica waveguide cover?

❌ No. This is dangerous and can damage the magnetron or start a fire.

Can I clean a burnt waveguide cover?

Only if it’s lightly dirty. Burnt or carbonized covers must be replaced.

Is replacing the waveguide cover safe?

Yes. It’s one of the safest microwave repairs when done with the unit unplugged.

Final Verdict: Small Part, Big Savings

Replacing a microwave waveguide cover is the cheapest, fastest, and smartest way to fix a sparking microwave.

For KES 300, you:

  • Eliminate the most common sparking cause
  • Diagnose deeper faults accurately
  • Avoid unnecessary magnetron replacement

👉 Order Your Microwave Waveguide Cover Today

  • 0768679055 Call or WhatsApp Instant Device. Nationwide delivery available.